It can be extremely difficult to monitor the growth of thin films, particularly if there is a need for to obtain two-dimensional imaging of the surface mechanical properties. Surface and interface coverages of only a few molecular layers are particularly difficult to sense. The surface mechanical properties, such as thickness, roughness, etc., are particularly difficult to determine given the small signal to background ratios associated with those films, surfaces and interfaces.
The only means to perform this type of metrology in an in-situ format is to use optical technologies, such as microscopy. But these optical technologies rely on linear optical responses, which are not optimal for surface characterization. As a result, existing solutions are mostly based on heuristic and historical processes. There are some in-situ diagnostic solutions which can show that a characteristic has changed, but these solutions are incapable of identifying what characteristic has changed.
Accordingly, there is a need for a testing system which addresses the drawbacks identified above.